The present invention concerns novel derivatives of thiadiazole compounds. More particularly, the new thiadiazoles are derived from 2,5-dimercapto-1,3,4-thiadiazole and terpene compounds. The invention further concerns improved lubricating compositions containing certain reaction products of 2,5-dimercapto-1,3,4-thiadiazole and terpene compounds.
Additives known as antiwear agents are employed to increase the load-carrying capacity of lubricants. The antiwear agents promote the formation of a surface film and thereby prevent wear of the contacting surfaces.
During the course of use, lubricants are susceptible to deterioration due to oxidation. The oxidative process leads to the loss of lubricating properties and inadequate protection of the device to be lubricated. Antioxidants are added to inhibit the oxidative process. Thus, it is desirable that antiwear agents possess antioxidant properties.
The most commonly used additives to exhibit antiwear and antioxidant properties are zinc dihydrocarbylphosphorodithioates. However, due to stricter environmental controls, it is particularly desirable to reduce the phosphorus content in lubricants. There is a need to develop improved lubricating compositions that are environmentally sound.
It has been surprisingly discovered that the foregoing disadvantages of the prior art lubricants can be eliminated by replacing all or part of the phosphorus-containing additive with certain terpene derivatives of 2,5-dimercapto-1,3,4-thiadiazoles. Particularly useful are novel 2-terpene derivatives of 5-hydrocarbylthio-2-mercapto-1,3,4-thiadiazoles and the known mono- and diterpene derivatives of 2,5-dimercapto-1,3,4-thiadiazoles. The latter have been disclosed as corrosion inhibitors in U.S. Pat. No. 2,764,547 to Fields.